How to add a border to a single videoclip
Blender can do all of those things but it takes a little bit of extra effort to set up. There is no "outline" tool, so you make it with a mask.


Create a mask in the UV/Image editor (render a frame from the video as a guide f-12), make sure that it is 'reversed' by clicking the Invert Mask button in the mask properties panel





Shift - A Add a "Color" effect strip above the video you want to highlight and apply a strip modifier in it's Strip Properties panel N key. Set the color strip's "Blend" type to Alpha Over or Over Drop.





To move them around the screen, (1) select both strips and combine them as a Metastrip ctrl-G. (2) Select the metastrip and add a Transform effect strip Shift-A. Select this new effect strip and change its "Blend" type to Alpha over or Over Drop the image or video (3) placed at the bottom of your stack. Use the properties panel to move and keyframe any animation.